Patent FR-A-2 470 275 in particular already discloses a clamp constituted by a band of metal wound on itself and presenting at its two ends complementary means for tightening and fastening the clamp in the tightened position. This prior Patent proposes providing, in the band constituting the clamp, an undulation extending over the whole width of the band and projecting outwardly. It makes it possible to give the clamp, after it has been mounted and tightened on a hose pipe, the capacity elastically to deform its periphery in the sense of a reduction in its length. The clamp may thus be adapted to a reduction in the outer periphery of the hose pipe, for example in the event of the material of said pipe creeping, whilst continuing to exert thereon a sufficient tightening force. This type of clamp is frequently called a "clamp having a reserve of capacity".
However, two drawbacks of this type of clamp have been observed.
On the one hand, particularly in the case of small-diameter clamps, the tool which is intended to tighten and fasten the two ends of the clamp abuts on the undulation instead of coming into contact with the stops allowing tightening. The tightening and fastening operation is thus more difficult.
On the other hand, if the clamp has to present a large "reserve of capacity", the radial projection of the undulation may attain prohibitive dimensions and it is not always possible to provide two or more undulations. This will be the case in particular if continuity of the inner periphery of the clamp must be maintained, for example by means of a suitable extension of the inner end of the band constituting the clamp.
Patent FR-A-2 616 879 has already proposed a first solution which partly overcomes the drawbacks which have just been set forth, but this solution cannot always be used in view of the increasingly strict requirements of the art.
Furthermore, Patent DE-A-1 091 821 proposes reinforcing an undulation of the band by means of a longitudinal rib, located in the vicinity of the crest of the undulation and extending substantially symmetrically with respect to this crest.
This solution does not avoid the drawbacks set forth hereinabove and, in particular, generally does not provide a "reserve of capacity" corresponding to the present requirements of the art.
Finally, it is obvious that the application of the solution proposed by this German Patent to the clamps according to one or the other of the French Patents mentioned hereinbefore, does not solve the two technical problems mentioned above.
It is therefore an object of the invention to provide a clamp with a reserve of capacity, of the type which has just been recalled, which eliminates its drawbacks whenever the first solution set forth is not suitable.